haveged

A Linux entropy source using the HAVEGE algorithm

A Linux entropy source using the HAVEGE algorithm

Haveged is a user space entropy daemon which is not dependent upon the
standard mechanisms for harvesting randomness for the system entropy
pool. This is important in systems with high entropy needs or limited
user interaction (e.g. headless servers).

Haveged uses HAVEGE (HArdware Volatile Entropy Gathering and Expansion)
to maintain a 1M pool of random bytes used to fill /dev/random
whenever the supply of random bits in /dev/random falls below the low
water mark of the device. The principle inputs to haveged are the
sizes of the processor instruction and data caches used to setup the
HAVEGE collector. The haveged default is a 4kb data cache and a 16kb
instruction cache. On machines with a cpuid instruction, haveged will
attempt to select appropriate values from internal tables.